Title : Hydrogen/Deuterium Exchange Mass Spectrometry of Human Green
Opsin Reveals a Conserved Pro-Pro Motif in Extracellular Loop 2 of Monostable Visual
G Protein-Coupled Receptors
Abstract :
- Opsins comprise the protein component of light sensitive G protein-coupled receptors ( GPCRs ) in the retina of the eye that are responsible for the transduction of light into a biochemical signal
- Here, we used hydrogen/deuterium (H/D) exchange coupled with mass spectrometry to map conformational changes in green cone opsin upon light activation
- We then compared these findings with those reported for rhodopsin
- The extent of H/D exchange in green cone opsin was greater than in rhodopsin in the dark and bleached states, suggesting a higher structural heterogeneity for green cone opsin
- Further analysis revealed that green cone opsin exists as a dimer in both dark (inactive) and bleached (active) states, and that the predicted glycosylation sites at N32 and N34 are indeed glycosylated
- Comparison of deuterium uptake between inactive and active states of green cone opsin also disclosed a reduced solvent accessibility of the extracellular N-terminal region and an increased accessibility of the chromophore binding site
- Increased H/D exchange at the extracellular side of transmembrane helix four (TM4) combined with an analysis of sequence alignments revealed a conserved Pro-Pro motif in extracellular loop 2 (EL2) of monostable visual GPCRs
- These data present new insights into the locus of chromophore release at the extracellular side of TM4 and TM5 and provide a foundation for future functional evaluation
Output (sent_index, trigger,
protein,
sugar,
site):
- 5. glycosylated, , -, -, sites
- 5. glycosylation, , -, -, N32 and N34
- 5. glycosylation, , -, -, sites
Output(Part-Of) (sent_index,
protein,
site):
*Output_Site_Fusion* (sent_index,
protein,
sugar,
site):